Brain circuitry expands and matures at an extraordinary rate during the ages just prior to puberty, from 7-12 years. During this time, many children develop many important cognitive and visual skills that are essential for reading. Not all children develop the ability to read, and for some children their difficulty is likely to be due to improper development within a small number of regions located in visual cortex. With the development of new brain imaging technologies, it is possible to safely measure children's brain development. This set of studies will identify the portions of the central visual pathways that are essential for reading (in adult) and also trace the normal development of these pathways (in children). These studies combine measurements of brain function and structure with psychological test of reading and mental development. The study follows the development of a group of 55 children with a wide range of reading skills. We anticipate that the range of reading skill development will be mirrored in a range of brain development rates within the portions of the brain that are essential for reading. By measuring behavior and brain development together, in each of the 55 children, we hope to understand healthy cortical development and how deviations from normal development explain reading disabilities. Public Information: Brain circuitry expands and matures at an extraordinary rate during the ages just prior to puberty. This is also the age range over which children develop many important cognitive skills such as reading. We combine neuroimaging measurements of (a) functional responses to simple stimuli, (b) anatomical development of the neural circuitry, with (c) careful behavioral assessments of reading to better understand the connection between behavior and brain development.